Multi-factor and Multi-object Optimization for Foundation Brake Device in Railway Freight Car

It is one of the important measures for improving the operational performance of the basic brake device to ensure the safety of railway freight cars. The operational performance of basic brake device includes braking performance and mitigation performance, which are affected by multi-factor such as lever size, sleeve clearance, installation angle and so on. Therefore, a multi-factor and multi-object optimization method that based on iSIGHT and multi-body dynamics simulation is proposed. The object of optimization is to minimize the transverse displacement of the brake beam and the mitigation force, and maximize the transmission efficiency. Firstly, identify the key factors such as the thickness of fixed lever, the width of back groove of middle tie rod, and the inner diameter of bushing 3 and bushing 4 by the main effect value of orthogonal test. Then, the Latin hypercube sampling points are applied for numerical simulation to establish the response surface model. The optimal solution set is obtained by NSGA-II multi-objectives genetic algorithm cyclic approximation optimization. The optimization scheme is selected by the target importance and the distribution probability of the optimal solution set. Finally, the optimization model is validated in RecurDyn. The optimized scheme achievement shows that the transverse displacement of the brake beam is reduced by 31%, the maximum reduction in mitigation power is 36% and the transmission efficiency is increased by 2%.